ADAPTATION: Some species that evolve in only in one 
place are valuable to researchers... learn why ... on 
Passport to Texas ... 
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Passport to Texas from Texas Parks and Wildlife

Sometimes animal species evolve in specific locations -- in 
natural springs, for example - to be found nowhere else 
in the world. So we asked fisheries research biologist Dr. 
Garry Garrett how this phenomenon occurs.

"Typically what happens is you have the ancestral version of the 
species throughout. Things like head springs, or spring areas, 
those are special isolated type environments. The temperature 
doesn't change; the water chemistry doesn't change because 
it's coming out of the ground. So you'll have animals that start 
specializing for that very stable environment. So certainly in 
springs throughout the state we've often seen specialized 
animals."

Biologists look at the adaptations and try to understand 
how these species specialize for specific environments.

"But the other real useful thing about understanding this is these 
are called indicator species. They've been around for thousands 
of years ... they've done just fine ... as biologists we monitor their 
status. When we see their status starting to go down, it tells us 
that the environment they're in is going down. Not just them. 
They're an indicator of a larger problem. So by watching these 
animals or plants they tell us in advance of things degrading 
that ultimately may affect humans. So they're kind of our early 
warning system."

That's our show for today ... thank you for joining us. Joel 
Block engineers our program.

For Texas Parks and Wildlife ... I'm Cecilia Nasti.